Parkinson's disease is a dopaminergic neurodegenerative disorder which afflicts an estimated 1% of the population over the age of fifty. The disease is primarily characterized by tremor, rigidity, impaired postural reflexes, and paucity of movement resulting from the loss of dopaminergic neurons in the substantia nigra which normally project to the corpus striatum. Because parkinsonian patients have a low concentration of dopamine in this region of the basal ganglia, current therapies have been directed at restoring normal levels of dopamine using the dopamine precursor L-dopa, with a peripheral decarboxylase inhibitor such as carbidopa. However, L-dopa's effectiveness diminishes with continued use and troublesome side effects often occur. Thus, alternative therapies are being sought. Strategies to promote functional recovery by implantation of fetal dopaminergic cells in specific dopamine-depleted areas of the brain are currently being evaluated in Parkinsonian animal models as well as in certain patients with Parkinson's disease. No doubt this investigational treatment will be confronted with some opposition on moral grounds.
The present invention has been accomplished with the above disadvantages in mind.